I. Field
The following description relates generally to wireless communications, and more particularly to providing a mechanism for repeating ACK for a receive data transmission using a transmission pattern.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, . . . ). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP LTE systems, orthogonal frequency division multiplexing (OFDM), localized frequency division multiplexing (LFDM), orthogonal frequency division multiple access (OFDMA) systems, and the like.
In a wireless communication system, a Node B (or base station) may transmit data to a user equipment (UE) on the downlink and/or receive data from the UE on the uplink. The downlink (or forward link) refers to the communication link form the Node B to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the Node B. The Node B may also send control information (e.g., assignments of system resources) to the UE. Similarly, the UE may send control information to the Node B to support data transmission on the downlink and/or other purposes.
In state of art systems, a hybrid automatic retransmission (HARQ) process is employed to improve reliability of data transmission (e.g. data packets or data assignment packets). In the system using HARQ process, the transmitter transmits data packets to a receiver and the receiver transmits acknowledgement (ACK if the data packets are processed successfully or NAK if the data packets are not processed successfully) in response. After the transmitter transmits the data packet, the transmitter awaits for reception of the ACK/NAK for a preset period of time before automatically retransmitting the data packet. If transmitter receives the ACK before the timer expires, the transmitter ends the HARQ process and begins another one, if any. If transmitter receives the NAK or the timer expires, the transmitter sets up another HARQ process and retransmits the data packet. However, if the ACK was transmitted by the receiver, but the transmitter was not able process it or did not receive the ACK before the time expired or the ACK/NAK transmissions are not reliable, the transmitter sets up another HARQ process and retransmits the data packet. This is very inefficient and causes delays in delivery of data. Thus, it is desirable to improve the reliability of ACK/NAK transmissions using an ACK/NAK repetition scheme, using an efficient transmission pattern in frequency and time to transmit ACK/NAK in order to improve system performance.